LuaJIT: Get function name and the currently executing line

perforator/agent/collector/pkg/profile/builder.go

@@ -481,6 +481,8 @@ type InterpreterLocationKey struct {
 	Linestart     int32
 	Line          int32
 	Language      models.Language
+	// Lua function names depend on the caller, even for the same proto and line.
+	Name string
 }
 
 type functionKey struct {

perforator/agent/collector/pkg/profiler/native_runtime.go

@@ -77,7 +77,7 @@ func (r *nativeRuntimeResolver) resolveInterpreterSection(key linux.ProcessKey,
 		if r.lua == nil {
 			return fmt.Errorf("interpreter resolver is unavailable")
 		}
-		err = resolveInterpreterSection(r.lua.ResolveFrame, key, section, writer)
+		err = resolveLuaSection(r.lua.ResolveFrame, key, section, writer)
 	default:
 		return fmt.Errorf("unsupported interpreter language %d", section.Language)
 	}
@@ -203,6 +203,31 @@ func resolveInterpreterSection[T runtimeFrame](resolve func(linux.ProcessKey, *T
 	return nil
 }
 
+func resolveLuaSection(resolve func(linux.ProcessKey, *unwinder.LuaFrame, *unwinder.LuaFrame, runtimewriter.Frame) error, key linux.ProcessKey, section nativepipeline.LanguageSection, writer *runtimewriter.Writer) error {
+	frames, err := viewRuntimeFrames[unwinder.LuaFrame](section)
+	if err != nil {
+		return err
+	}
+	for i := range frames {
+		output, err := writer.AddFrame(0, 1)
+		if err != nil {
+			return err
+		}
+
+		var callerFrame *unwinder.LuaFrame
+
+		// Frames run from callee to caller. The caller's PC names callee's frame.
+		if i+1 < len(frames) {
+			callerFrame = &frames[i+1]
+		}
+
+		if err := resolve(key, &frames[i], callerFrame, output); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // Frames borrow the BPF payload for the synchronous resolver call.
 func viewRuntimeFrames[T runtimeFrame | unwinder.JvmFrame](section nativepipeline.LanguageSection) ([]T, error) {
 	var frame T

perforator/agent/collector/progs/unwinder/arch/x86/regs.h

@@ -17,6 +17,7 @@ struct user_regs {
     u64 rdi;
     u64 rdx;
     u64 r14;
+    u64 rbx;
 };
 
 static ALWAYS_INLINE u64 regs_get_current_instruction(struct user_regs* regs) {
@@ -30,6 +31,7 @@ struct pt_regs___kernel {
     u64 di;
     u64 dx;
     u64 r14;
+    u64 bx;
 };
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -75,6 +77,7 @@ static NOINLINE bool extract_saved_userspace_registers(struct user_regs* regs) {
     regs->rdi = BPF_CORE_READ(kregs, di);
     regs->rdx = BPF_CORE_READ(kregs, dx);
     regs->r14 = BPF_CORE_READ(kregs, r14);
+    regs->rbx = BPF_CORE_READ(kregs, bx);
 
     return true;
 }
@@ -90,6 +93,7 @@ static NOINLINE bool find_task_userspace_registers(struct pt_regs* kregs, struct
     uregs->rdi = kregs->rdi;
     uregs->rdx = kregs->rdx;
     uregs->r14 = kregs->r14;
+    uregs->rbx = kregs->rbx;
 
     return true;
 }